Resource allocation

ABSTRACT

A method of signalling resource allocation data in a communication system which uses a plurality of sub-carriers arranged in a sequence of chunks. An allocation of the sub-carriers for each of a plurality of user devices is received. The received allocations are processed to determine, for each user device, data identifying a start chunk and an end chunk within the sequence of chunks, which depend upon the sub-carriers allocated to the user device. Different resource allocation data is generated for each of the user devices using a predetermined mapping which relates the data identifying the corresponding start chunk and end chunk determined by the processing step to resource allocation data comprising a unique value. The respective resource allocation data is signaled to each of the plurality of user devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.13/137,991 filed Sep. 23, 2011, which application is a Continuation ofU.S. application Ser. No. 12/225,236 filed Sep. 17, 2008, now U.S. Pat.No. 8,310,998, which is the national stage of International ApplicationNo. PCT/JP2007/056524, filed Mar. 20, 2007, which claims priority toGreat Britain Application No. 0605581.8, having filing date of Mar. 20,2006, all of which are incorporated herein by reference.

DESCRIPTION

Field of the Invention

The present invention relates to the signalling of resource allocationswithin a communication system. The invention has particular, althoughnot exclusive relevance to the signalling of sub-carriers used in anorthogonal frequency divisional multiple access (OFDMA) communicationsystem.

Background of the Invention

OFDMA and single carrier FDMA have been selected as the downlink anduplink multiple access schemes for the E-UTRA air interface currentlybeen studied in 3GPP (which is a standard based collaboration looking atthe future evolution of third generation mobile telecommunicationsystems). Under the E-UTRA system, a base station which communicateswith a number of user devices allocates the total amount oftime/frequency resource (depending on bandwidth) among as manysimultaneous users as possible, in order to enable efficient and fastlink adaptation and to attain maximum multi-user diversity gain. Theresource allocated to each user device is based on the instantaneouschannel conditions between the user device and the base station and isinformed through a control channel monitored by the user device.

SUMMARY OF THE DISCLOSURE

In order to support a large number of users devices, an efficientmechanism of resource signalling utilizing the least possibletime/frequency resource is necessary.

And thus there is much desired in the art to provide a novel method forsignalling resource allocation data in a communication system,communication node (or station), user devices therefore, acomputer-readable program for operating the method and apparatus,devices and/or system.

According to a first aspect, the present invention provides a method ofsignalling resource allocation data in a communication system which usesa plurality of sub-carriers arranged in a sequence of chunks, the methodcomprising: receiving an allocation of the sub-carriers for each of theuser devices; processing the received allocations to determine, for eachuser device, data identifying a start chunk and an end chunk within thesequence of chunks, which depend upon the sub-carriers allocated to theuser device; generating respective resource allocation data for each ofthe user devices using said data identifying the corresponding startchunk and end chunk determined by the processing step; and signallingthe respective resource allocation data to each of the plurality of userdevices.

Each of the user devices can then determine its allocated sub-carriersby receiving the resource allocation data identifying the start chunkand end chunk within the sequence of chunks and by relating this data tothe sub-carrier allocation using information held or defined within theuser device.

In one mode, the resource allocation data includes a bit pattern whichdefines a grouping of the sequence of chunks into a sequence of groupsin dependence upon the sub-carriers allocated to the user devicestogether with a resource ID which identifies the group of chunksallocated to that user device. In this case the resource ID preferablydepends on the position of the group within the sequence of groups.

In an alternative mode, the resource allocation data comprises a uniquevalue related to the combination of the start chunk and end chunk of anallocated group of chunks. For some allocations, the group of chunks maycomprise a single chunk, in which case the start chunk and end chunkwill be the same. The data identifying the start and end chunk mayidentify these chunks either directly or indirectly. For example, thedata identifying these chunks may identify the start chunk or the endchunk and the number of chunks between the start chunk and end chunk.

In a preferred mode, a number of different types of sub-carrierallocations can be made. In this case, the processing performed in theencoder and the processing performed in the decoder will depend on theallocation type that is used and data identifying the allocation typewill also have to be signalled to the user devices, so that they canperform the appropriate processing of the received resource allocationdata.

For resource allocation, efficient encoding techniques are necessary forencoding resource allocation data to be signalled to a number of userdevices in a communication system. In one encoding technique, a resourceallocation bit pattern is transmitted to all the users together with aresource ID for each user. Each user then identifies its allocatedsub-carriers using the received allocation bit pattern and the receivedresource ID. In another encoding technique, a code tree is used togenerate a value representing the sub-carrier allocation. The userdevice then uses the code tree to determine the sub-carrier allocationfrom the signalled value.

The generating step may include: generating a bit pattern which definesa grouping of the sequence of chunks into a sequence of groups, independence upon the sub-carriers allocated to each user device;generating a resource ID for each group in dependence upon the positionof the group within the sequence of groups; and wherein the allocationdata for a user device comprises the bit pattern and a respectiveresource ID.

The signalling step may signal the bit pattern in a signalling channelcommon to the user devices.

The signalling step may signal the resource ID for a user device in asignalling channel dedicated to that user device.

The bit pattern may include a bit associated with each of the second andsubsequent chunks in the sequence of chunks, whose value defines whetheror not the associated chunk is the start of a new group in the sequenceof groups.

The bit pattern may comprise N−1 bits, where N is the number of chunksin the sequence of chunks.

The resource ID for a group may identify the group by its positionwithin the sequence of groups.

The generating step may comprise using a predetermined mapping whichrelates the data identifying the start and end chunks for a user deviceto a unique value, and the resource allocation data for the user devicemay comprise the value.

The mapping may be defined by one or more equations.

The mapping may be defined by the following expression:

${{if}\mspace{14mu}\left( {P - 1} \right)} \leq \left\lceil \frac{N}{2} \right\rceil$  x = N(P − 1) + O else   x = N(N − (P − 1)) + (N − 1 − O)where ┌ ┐ is the ceiling function, N is the number of chunks in thesequence, O is the start chunk and P is the number of consecutivechunks.

The mapping may be defined by a data structure that defines a code treecomprising a plurality of leaf nodes and having a depth corresponding tothe number of chunks in the sequence of chunks.

The mapping may be defined by a look up table.

The signalling step may signal the resource allocation data for a userdevice in a signalling channel that is dedicated to the user device.

The received data may identify a type of allocation of the sub-carriers,wherein the processing performed in the processing step depends on theidentified type of allocation, and the generating step may generateresource allocation data that includes type data identifying the type ofallocation.

One type of allocation may be a localised chunk allocation, in which auser device is allocated a set of consecutive chunks of sub-carriers.

One type of allocation may be a distributed chunk allocation, in which auser device is allocated a set of the chunks dispersed within itssupported bandwidth.

One type of allocation may be a distributed carrier allocation, in whicha user device is allocated a set of possibly discontinuous sub-carriersdispersed within its supported bandwidth.

The generating step may be operable to encode an identifier of thedetermined start chunk and an identifier of the determined end chunkwhen generating the resource allocation data.

The communication system may use a plurality of sub-bands, each of whichcomprises sub-carriers arranged in a sequence of chunks, and the methodmay generate respective resource allocation data for sub-carrierallocation in each sub-band.

The resource allocation data for a sub-band may be signalled within thatsub-band.

According to a second aspect, the present invention provides a method ofdetermining carrier frequency allocation in a communication system whichuses a plurality of sub-carriers arranged in a sequence of chunks, themethod comprising: receiving resource allocation data identifying astart chunk and an end chunk within the sequence of chunks; holdinginformation which relates resource allocation data to the sequence ofchunks of sub-carriers; and determining the allocated sub-carriers usingthe received resource allocation data and the held information.

The receiving step may receive resource allocation data comprising: abit pattern and a resource ID aforementioned in the first aspect. Thatis the resource allocation data comprises; a bit pattern which defines agrouping of the sequence of chunks into a sequence of groups, independence upon the sub-carriers allocated to each user device; and aresource ID for one of the groups, which resource ID depends upon theposition of that group within the sequence of groups.

The receiving step may receive the bit pattern in a common signallingchannel common of the communication system.

The receiving step may receive the resource ID in a dedicated signallingchannel of the communication system.

The bit pattern may include a bit associated with each of the second andsubsequent chunks in the sequence of chunks, whose value defines whetheror not the associated chunk is the start of a new group in the sequenceof groups.

The bit pattern may comprise N−1 bits, where N is the number of chunksin the sequence of chunks.

The received resource ID may identify the one of the groups by itsposition within the sequence of groups.

The determining step may use the resource ID to identify the positionsof associated bits within the bit pattern and to determine the start andend chunks from the determined bit positions.

The receiving step may comprise receiving resource allocation data whichcomprises a value which is related to data identifying the start and endchunks through a predetermined mapping, wherein the held informationdefines the mapping and wherein the determining step determines thesub-carrier allocation using the received resource allocation data andthe mapping.

The mapping may be defined by one or more equations.

The determining step may determine a value, O, corresponding to thestart chunk and a value, P, identifying the number of consecutive chunksbetween the start chunk and the end chunk from the following expression:

$a = {\left\lfloor \frac{x}{N} \right\rfloor + 1}$ b = x mod Nif (a + b > N)   P = N + 2 − a   O = N − 1 − b else   P = a   O = b

where ┌ ┐ is the floor function, N is the total number of chunks in thesequence and x is the received value, and wherein the determining stepmay determine the sub-carrier allocation using the values, O and P, thusobtained.

The mapping may be defined by a data structure that defines a code treecomprising a plurality of leaf nodes and having a depth corresponding tothe number of chunks in the sequence of chunks.

The mapping may be defined by a look up table.

The receiving step may receive the resource allocation data in adedicated signalling channel of the communication system.

The received resource allocation data may comprise data that identifiesa type of allocation of the sub-carriers, and the determination made inthe determining step may depend upon the identified type of allocation.

One type of allocation may be a localised chunk allocation, in which auser device is allocated a set of consecutive chunks of sub-carriers,and the determining step may determine the sub-carrier allocation asbeing the set of contiguous sub-carriers of the chunk or chunks withinand between the identified start and end chunks.

One type of allocation may be a distributed chunk allocation, in which auser device is allocated a set of distributed chunks of sub-carriers,and the determining step may comprise the steps of determining thenumber of chunks between the identified start and end chunks anddetermining a chunk spacing by dividing the total number of chunks inthe sequence by the number of chunks between the identified start andend chunks.

The determining step may determine a start chunk in dependence uponchunk allocations for other user devices.

One type of allocation may be a distributed sub-carrier allocation, inwhich a user device is allocated a set of distributed sub-carriers, andthe determining step may comprise the steps of determining the number ofchunks between the identified start and end chunks and determining asub-carrier spacing by dividing the total number of chunks in thesequence by the number of chunks between the identified start and endchunks.

The determining step may determine a start sub-carrier in dependenceupon sub-carrier allocations for other user devices.

The communication system, may use a plurality of sub-bands, each ofwhich may comprise sub-carriers arranged in a sequence of chunks, andwherein the method receives respective resource allocation data forsub-carrier allocation in a plurality of the sub-bands.

The resource allocation data for a sub-band may be received within thatsub-band.

The allocation data may be encoded and the determining step may comprisethe step of decoding the allocation data to determine the start and endchunks or to identify data defining the start and end chunks.

According to a third aspect, there is provided a communication node(station) which is operable to communicate with a plurality of userdevices using a plurality of sub-carriers arranged in a sequence ofchunks and which is operable to signal sub-carrier allocations to eachof the user devices using a method according to any of the first aspect.

According to a fourth aspect, there is provided a user device which isoperable to communicate with the communication node (station) of thethird aspect and which is operable to determine a sub-carrier allocationusing the method of any of the second aspect.

According to a fifth aspect, there are provided computer implementableinstructions for causing a programmable computer device to perform thesignalling method of any of the first aspect.

According to a sixth aspect, there are provided computer implementableinstructions for causing a programmable computer device to perform themethod of determining sub-carrier allocation of any of the secondaspect.

The computer implementable instructions of the fifth or sixth aspect maybe recorded on a computer readable medium.

According to a seventh aspect, specifically, there is provided acommunication node (or station) which is operable to communicate with aplurality of user devices using a plurality of sub-carriers arranged ina sequence of chunks, the communications node comprising: a receiveroperable to receive an allocation of the sub-carriers for each of aplurality of user devices; a processor operable to process the receivedallocations to determine, for each user device, data identifying a startchunk and an end chunk within the sequence of chunks, which depend uponthe sub-carriers allocated to the user device; a generator operable togenerate respective resource allocation data for each of the userdevices using the data identifying the corresponding start chunk and endchunk determined by the processor; and an output operable to output therespective resource allocation data to each of the plurality of userdevices.

According to an eighth aspect, specifically, there is provided a userdevice which is operable to communicate with a communication node whichis operable to communicate with a plurality of user devices using aplurality of sub-carriers arranged in a sequence of chunks, the userdevice comprising: a receiver operable to receive resource allocationdata identifying a start chunk and an end chunk within the sequence ofchunks; a memory or circuit operable to hold information relating theresource allocation data to the sequence of chunks; and a determineroperable to determine the allocated sub-carriers using the receivedresource allocation data and the held information.

According to further aspect, there are provided; a method of orapparatus for signalling sub-carrier allocations substantially asdescribed herein with reference to or as shown in the accompanyingfigures; and a method of or apparatus for receiving and decoding asub-carrier allocation substantially as described herein with referenceto or as shown in the accompanying figures.

These and various other aspects of the invention will become apparent,from the following detailed description of modes which are given by wayof example only and which are described with reference to theaccompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates a communication system comprising anumber of user mobile (cellular) telephones which communicate with abase station connected to the telephone network;

FIG. 2 illustrates the way in which a communication bandwidth of thebase station shown in FIG. 1 can be allocated to a number of differentmobile telephones having different supported bandwidths:

FIG. 3 is a block diagram illustrating the main components of the basestation shown in FIG. 1;

FIG. 4 illustrates the way in which chunks of sub-carriers within a 5MHz sub-band can be grouped into a plurality of groups for allocation tothe different mobile telephones;

FIG. 5A illustrates the way in which sub-carriers can be allocated basedon a localised allocation in which each mobile telephone is allocated aset of consecutive chunks of sub-carriers;

FIG. 5B illustrates the way in which the same encoding technique can beused to allocate the sub-carriers using a distributed chunk allocationin which each mobile telephone is allocated a set of chunks dispersedacross its supported bandwidth;

FIG. 5C illustrates the way in which the same encoding technique can beused to allocate the sub-carriers using a distributed sub-carrierallocation in which each mobile telephone is allocated a set of possiblydiscontinuous sub-carriers dispersed across its supported bandwidth;

FIG. 6 is a flow chart illustrating the processing carried out by anencoder module forming part of the base station shown in FIG. 3;

FIG. 7 is a block diagram illustrating the main components of one of themobile telephones shown in FIG. 1;

FIG. 8 is a flow chart illustrating the main processing steps carriedout by a decoder nodule forming part of the mobile telephone shown inFIG. 7;

FIG. 9 illustrates the way in which chunks of sub-carriers within a 2.5MHz sub-band can be grouped into a plurality of groups for allocation tothe different mobile telephones; and

FIG. 10 schematically illustrates a code tree that is used by theencoder module of the base station in an alternative mode to encode astart and end chunk defining the sub-carrier allocation for a user.

MODES CARRYING OUT THE INVENTION

Overview

FIG. 1 schematically illustrates a mobile (cellular) telecommunicationsystem 1 in which users of mobile telephones 3-0, 3-1, and 3-2 cancommunicate with other users (not shown) via a base station 5 and atelephone network 7. In this mode, the base station 5 uses an orthogonalfrequency division multiple access (OFDMA) technique in which the datato be transmitted to the mobile telephones 3 is modulated onto aplurality of sub-carriers. Different sub-carriers are allocated to eachmobile telephone 3 depending on the supported bandwidth of the mobiletelephone 3 and the amount of data to be sent to the mobile telephone 3.In this mode the base station 5 also allocates the sub-carriers used tocarry the data to the respective mobile telephones 3 in order to try tomaintain a uniform distribution of the mobile telephones 3 operatingacross the base station's bandwidth. To achieve these goals, the basestation 5 dynamically allocates sub-carriers for each mobile telephone 3and signals the allocations for each time point (sub-frame) to each ofthe scheduled mobile telephones 3.

FIG. 2 illustrates an example of the way in which the base station 5 canallocate sub-carriers within its supported bandwidth to different mobiletelephones 3 having different supported bandwidths. In this mode, thebase station 5 has a supported bandwidth of 20 MHz of which 18 MHz isused for data transmission. In FIG. 2, MT represents, mobile terminal.

In order that each of the mobile telephones 3 can be informed about thescheduling decision within each sub-band, each mobile telephone 3requires a shared control channel within its camped frequency band. Theinformation signalled within this control channel will include:

-   -   i) resource block allocation information (for both downlink        communications and uplink communications);    -   ii) resource block demodulation information for the downlink;    -   iii) resource block demodulation information for the uplink;    -   iv) ACK/NACK for uplink transmissions; and    -   v) timing control bits.

Since the number of bits available in the control channel is limited,efficient methods are needed to transport the required information withthe lowest number of bits. The invention relates to the way in which theresource allocation information can be signalled in an efficient mannerto each of the mobile telephones 3.

Base Station

FIG. 3 is a block diagram illustrating the main components of the basestation 5 used in this mode. As shown, the base station 5 includes atransceiver circuit 21 which is operable to transmit signals to and toreceive signals from the mobile telephones 3 via one or more antennae 23(using the above described sub-carriers) and which is operable totransmit signals to and to receive signals from the telephone network 7via a network interface 25. The operation of the transceiver circuit 21is controlled by a controller 27 in accordance with software stored inmemory 29. The software includes, among other things, an operatingsystem 31 and a resource allocation module 33. The resource allocationmodule 33 is operable for allocating the sub-carriers used by thetransceiver circuit 21 in its communications with the mobile telephones3. As shown in FIG. 3, the resource allocation module 33 also includesan encoder module 35 which encodes the allocation into an efficientrepresentation which is then communicated to the respective mobiletelephones 3.

In this mode, the base station 5 can use three different types ofsub-carrier allocation:

i) a localised chunk allocation in which each mobile telephone 3 isallocated a set of consecutive chunks of sub-carriers, where, in thismode, each chunk is a set of 25 consecutive sub-carriers;

ii) a distributed chunk allocation in which each mobile telephone 3 isallocated a set of chunks dispersed across the bandwidth supported bythe mobile telephone 3; and

iii) a distributed sub-carrier allocation in which each mobile telephone3 is allocated a set of possibly discontinuous sub-carriers dispersedacross the bandwidth supported by the mobile telephone 3.

First Encoding Technique

A first encoding technique that the encoder module 35 can use to encodethe above described resource allocation information will now bedescribed with reference to FIGS. 4 to 6. FIG. 4 schematicallyillustrates the way in which the 300 sub-carriers within a 5 MHzsub-band of the base station's operating bandwidth are divided into asequence of twelve chunks (labeled: 0, 1, 2, 3, . . . 11), eachcomprising 25 sub-carriers. Information defining this arrangement ofchunks may be stored as data within the memory of the base station 5(and in the mobile telephones 3) or it may be defined in the software orhardware circuits running therein. FIG. 4 also illustrates the way inwhich the encoder module 35 partitions, in this mode, the chunks ofsub-carriers into a sequence of groups (in this case five groups),depending on the current sub-carrier allocation. In the exampleillustrated in FIG. 4, the first group comprises chunks 0 and 1; thesecond group comprises chunk 3; the third group comprises chunks 3 to 7;the fourth group comprises chunks 8 and 9; and the fifth group compriseschunks 10 and 11.

FIG. 4 also illustrates a resource allocation bit pattern 51 that isgenerated by the encoder module 35 and that defines this grouping of thechunks. As shown, the resource allocation bit pattern 51 includes onebit for each of the twelve chunks within the sub-band, which is set to avalue of “1” when the corresponding chunk is the first chunk in a newgroup and otherwise it is set to a value of “0”. As those skilled in theart will appreciate, the first bit of the twelve bit pattern 51 isredundant and does not need to be signalled (transmitted) because thefirst chunk within the sub-band will always be the first chunk withinthe first group.

FIG. 4 also illustrates a resource ID 53 which is provided for each ofthe defined groups. As shown, in this mode, the resource ID for a groupidentifies the group by its position within the sequence of groups. Inparticular, the resource IDs are implicitly numbered from left to rightcorresponding to the associated group's position within the sequence ofgroups.

Each mobile telephone 3 is then informed of its allocation within each 5MHz sub-band by signalling the corresponding resource allocation bitpattern 51 and one of the resource IDs 53. In this mode, the resourceallocation bit patterns 51 are signalled to the mobile telephones 3 overa common signalling channel in each 5 MHz sub-band and the resourceID(s) 53 for each mobile telephone 3 are individually signalled in itsdedicated control channel. In this mode, each resource ID 53 issignalled as a 3 bit number leading to a maximum number of eight mobiletelephones 3 that can be scheduled per 5 MHz sub-band. Mobile telephones3 with larger bandwidths can combine multiple 5 MHz sub-bands and decodetheir total resource allocation from the resource allocation bit pattern51 and the resource ID 53 from each sub-band.

As those skilled in the art will appreciate, the way in which theencoder module 35 generates the above described resource allocation bitpatterns 51 and resource IDs 53 will vary depending on how thesub-carriers have been allocated (i.e. using localised chunk allocation,distributed chunk allocation or distributed sub-carrier allocation).Examples of these different types of allocations will now be describedwith reference to FIG. 5.

Localised Chunk Allocation

FIG. 5A illustrates one example where the sub-carriers have beenallocated to the three mobile telephones 3 shown in FIG. 1 using alocalised chunk allocation. In particular, in this example, mobiletelephone 3-0 has a supported bandwidth of 10 MHz and is allocatedchunks 10 and 11 in the first sub-band and chunks 0 and I in the secondsub-band. Similarly, in this example, mobile telephone 3-1 has asupported bandwidth of 10 MHz and is allocated chunk 2 in the firstsub-band and chunks 3, 4, and 5 in the second sub-band. Note, the firstsub-band means the first 300 sub-carriers (labeled 51-1) in FIG. 5A, andthe second sub-band means the second 300 sub-carriers (labeled 51-2) inFIG. 5A. Finally, in this example, mobile telephone 3-2 has a supportedbandwidth of 5 MHz and is allocated chunks 3, 4, 5, 6 and 7 within thefirst sub-band. FIG. 5A shows the two different resource bit patterns51-1 and 51-2 and the corresponding resource IDs generated by theencoder module 35 for the two illustrated sub-bands. FIG. 5A alsoillustrates at the bottom of the figure the resource ID that issignalled to the respective mobile telephones 3. As each mobiletelephone 3 receives only 1 resource ID for each 5 MHz sub-band that itoccupies, its sub-carrier allocation is contiguous within each sub-band.However, a mobile telephone 3, having a 10 MHz supported bandwidth canbe assigned resources in each of the 5 MHz sub-bands it occupies, andthese resources need not be contiguous with each other, as illustratedin FIG. 5A for mobile telephone 3-1.

As discussed above, in this mode, it is assumed that at most eightmobile telephones 3 can be scheduled within each 5 MHz sub-band at eachtime point (sub-frame). It may therefore appear that there is someredundancy in the twelve bit resource allocation bit pattern 51 (whichcould allow up to twelve resource IDs to be defined within eachsub-band). However, even in the case that the maximum number of eightmobile telephones 3 are scheduled within a sub-band, it is stillpossible some sub-carriers are not used. For example, if eight mobiletelephones 3 are allocated one chunk of sub-carriers and the remaining 4unused chunks are not in a contiguous block, then up to twelve bits (oreleven if you ignore the first bit as discussed above) are still neededto define the partitioning of chunks to achieve the desired allocation.

Distributed Chunk Allocation

FIG. 5B illustrates the way in which the same type of resourceallocation bit pattern 51 and resource ID 53 can be used when adistributed chunk allocation scheme is employed. FIG. 5B illustrates theactual chunk allocation 61 for 5 different mobile telephones 3,identified by the different shadings. In the illustrated example, onemobile telephone 3 is allocated 6 chunks (namely chunks 0, 2, 4, 6, 8and 10); one mobile telephone is allocated 3 chunks (namely chunks 1, 5and 9); and the other 3 mobile telephones 3 are each allocated 1 chunkof sub-carriers. In this mode, to facilitate the decoding of theresource allocation data in the mobile telephones 3, the partitioning ofthe chunks is arranged in decreasing order in terms of the number ofchunks per group. For the example shown in FIG. 5B this means that thegroup comprising 6 chunks is positioned first, followed by the groupcomprising 3 chunks, followed by the 3 remaining groups each comprising1 chunk. As the resource IDs for these groups of chunks are numberedfrom left to right, this means that the mobile telephone 3 with thelargest number of allocated chunks is given the smallest ID, the userwith the second largest number of allocated chunks is given the nextsmallest ID etc. As will be apparent to those skilled in the art, thenumber of chunks allocated to each mobile telephone 3 needs to be aconsideration in the number of chunks allocated to other mobiletelephones 3 with a lower resource ID, in order to avoid resourcecollision during resource signalling decoding.

Distributed Sub-Carrier Allocation

FIG. 5C schematically illustrates an example of a distributedsub-carrier allocation that may be employed. As with the exampleillustrated in FIG. 5B, in the example shown in FIG. 5C, there are fivemobile telephones, with the first mobile telephone 3 been allocatedsub-carriers 0, 2, 4, . . . , 298; with the second mobile telephone 3been allocated sub-carriers 1, 5, 9, . . . 297; with the third mobiletelephone 3 been allocated sub-carriers 3, 15, . . . 291; with thefourth mobile telephone 3 been allocated sub-carriers 7, 19, . . . 295;and with the fifth mobile telephone 3 been allocated sub-carriers 11,23, . . . 299. In this illustrated example, the spacing between thesub-carriers allocated to the first mobile telephone 3 is two, thatbetween the sub-carriers allocated to the second mobile telephone 3equals 4 and that between the sub-carriers allocated to the 3 remainingmobile telephones equals 12. In this illustrative example, all themobile telephones 3 occupy the 6 available chunks but with differentsub-carrier spacing. The allocation is identical to the distributedchunk allocation repeated to span the entire S MHz bandwidth with thechunk bandwidth replaced by the sub25 carrier bandwidth. FIG. 5Cillustrates the resulting resource allocation bit pattern 51 andresource IDs 53 for this sub-carrier allocation.

Allocation Type Bits

As those skilled in the art will appreciate, in order that the mobiletelephones 3 can determine the correct sub-carrier allocation, they mustbe informed of the type of sub-carrier allocation that has been made(i.e. localised chunk allocation, distributed chunk allocation ordistributed sub-carrier allocation). This information is signalled toall of the mobile telephones 3 using the following two bit allocationtype pattern:

Allocation Type Pattern Allocation Type 0 0 Localised chunk 0 1Distributed chunk I 1 Distributed sub-carrier

As will be described in more detail below, the mobile telephones 3 usethis allocation type bit pattern to identify how they should interpretthe group of chunks that has been assigned to it, using the resourceallocation bit pattern 51 and the resource ID 53.

Summary of Encoder Module Operation

FIG. 6 is a flow chart illustrating the main processing steps carriedout by the encoder module 35 to determine the above described resourceallocation bit patterns 51 and resource IDs 53 for the different mobiletelephones 3 scheduled for a current time point. As shown, in step s1,the encoder module 35 receives the current sub-carrier allocation, whichincludes details as to whether or not the allocation is in accordancewith the localised chunk allocation scheme, distributed chunk allocationscheme or distributed sub-carrier allocation scheme. In step s3, theencoder module 35 partitions the chunks of sub-carriers in each of thebase station's four 5 MHz sub-bands into groups, based on the receivedsub-carrier allocation. As those skilled in the art will appreciate theprocessing performed in step s3 will depend on the type of sub-carrierallocation that has been performed. In step s5, the encoder module 35generates the above described resource allocation bit pattern 51 foreach 5 MHz sub-band, that represents the partition of chunks in thatsub-band. Then, in step s7, the encoder module 35 generates a resourceID for each group of chunks in each sub-band for signalling to thecorresponding mobile telephone 3.

After the resource IDs 53 have been generated for the groups of chunksin each 5 MHz sub-band, the processing proceeds to step s9 where theencoder module 35 signals (transmits) the generated resource allocationbit patterns 51 to all of the mobile telephones 3. In particular, inthis step, the encoder module 35 causes the transceiver circuit 21 tosignal, within a common signalling channel in each 5 MHz sub-band, theresource allocation bit pattern 51 representing the partitioning of thechunks within that sub-band. The mobile telephones 3 will therefore beable to receive the resource allocation bit patterns 51 for all thesub-bands in which they operate. For example, if mobile telephones 3-0and 3-1 have an operating bandwidth of 10 MHz and mobile telephone 3-2has an operating bandwidth of 5 MHz, then mobile telephones 3-0 and 3-1will receive two resource allocation bit patterns 51 within their commonsignalling channels and mobile telephone 3-2 will receive one resourcebit pattern 51 within its common signalling channel. The above describedtwo bit resource allocation type pattern is also transmitted with eachresource allocation bit pattern 51 in step s9. After step s9, theprocessing proceeds to step si 1 where the encoder module 35 signals therespective resource IDs 53 to each mobile telephone 3 within the mobiletelephone's dedicated signalling channel in each 5 MHz sub-band.

Therefore, with the first encoding technique for each 5 MHz sub-band, atotal of 14 common channel bits are signalled (13 if the first bit ofthe resource allocation pattern is not signalled) and three resource IDbits for each user device are signalled.

Mobile Telephone

FIG. 7 schematically illustrates the main components of each of themobile telephones 3 shown in FIG. 1. As shown, the mobile telephones 3include a transceiver circuit 71 which is operable to transmit signalsto and to receive signals from the base station 5 via one or moreantennae 73. As shown, the mobile telephone 3 also includes a controller75 which controls the operation of the mobile telephone 3 and which isconnected to the transceiver circuit 71 and to a loudspeaker 77, amicrophone 79, a display 81, and a keypad 83. The controller 75 operatesin accordance with software instructions stored within memory 85. Asshown, these software instructions include, among other things, anoperating system 87 and a communications module 89. In this mode, thecommunications module 89 includes a decoder module 91 which is operableto decode the resource allocation data signalled from the base station 5to determine that mobile telephone's sub-carrier allocation for thecurrent time point.

The way which the decoder module 91 decodes the resource allocation datareceived from the base station 5 will now be described with reference tothe flowchart shown in FIG. 8. As shown, in step s21, the decoder module91 receives the resource allocation bit pattern and the associated twobit allocation type pattern from each received common signallingchannel. As will be apparent from the above discussion, the number ofresource allocation bit patterns 51 and the number of allocation typepatterns received depends on the supported bandwidth of the mobiletelephone 3. In step s23, the decoder module 91 receives the resourceID(s) 53 from its dedicated signalling channel(s). The number ofresource IDs 53 received also depends on the supported bandwidth of themobile telephone 3. Then in step s25, the decoder module 91 identifies,for each supported 5 MHz sub-band, the start and end chunks of the groupof chunks associated with the resource ID 53 received for that sub-band.The decoder module 91 identifies these start and end chunks using thecorresponding resource allocation bit pattern 51 received for thatsub-band. For example, if the received resource ID 53 is the binaryvalue “010” corresponding to the resource ID “2”, then the decodermodule 91 processes the corresponding resource allocation bit pattern 51to identify the bit positions of the second and third “1s” counting fromthe left (and ignoring the first bit within the resource allocation bitpattern 51 if it includes 12 bits as the first bit always corresponds tothe start of the first group). The bit position of this second “1”identifies the beginning of the group having resource ID “2” and the bitposition of the third “1” identifies the chunk that is at the start ofthe next group within the sequence of groups, from which the decodermodule 91 can determine the end chunk of the group having resource ID“2”. In the example illustrated in FIG. 5A for the first sub-band, thesecond “1” in the resource bit allocation pattern 51 (ignoring the firstbit) is the fourth bit from the left hand end and the third “1” withinthe bit pattern 51 is the ninth bit from the left hand end. As can beseen from FIG. 5A, this means that the group of chunks corresponding tothe received resource ID of “2” comprises chunks 3 to 7 within that 5MHz sub-band.

Once the start and end chunks of the group associated with the receivedresource ID 53 have been determined, the processing proceeds to s27,where the decoder module 91 uses the received two bit allocation typepattern to determine if the allocation is a localised chunk allocation.If it is, then the processing proceeds to step s29 where the decodermodule 91 determines that the allocated sub-carriers correspond to thecontinuous set of sub-carriers within and between the identified startand end chunks. For the above example this will result in the decodermodule 91 allocating the sub-carriers within chunks 3 to 7 (inclusive),for communications with the base station 5.

If at step s27, the decoder module 91 determines that the two bitallocation type pattern does not correspond to a localised chunkallocation, then processing proceeds to step s31 where the decodermodule 91 determines if the two bit allocation type pattern correspondsto a distributed chunk allocation. If it does, then the processingproceeds to step s33 where the decoder module 91 uses the identifiedstart and end chunks to determine the chunk spacing by dividing thetotal number of chunks within the sub-band by the number of chunksbetween the identified start and end chunks. For example, for thedistributed chunk allocation illustrated in FIG. 5B and where thereceived resource ID 53 is “1”, the total number of chunks within thesub-band equals 12 and the number of chunks between the identified startand end chunks is 3. Therefore, 3 chunks are allocated within thissub-band that are spaced apart by 4 (12/3=4) chunks. The position of thefirst of these chunks within the sub-band depends on the sub-carrierallocation for other scheduled mobile telephones 3 within that sub-band.Consequently, when distributed chunk allocation has been selected, thedecoder module 91 also considers the chunk allocation for the othermobile telephones 3 scheduled at that time. The decoder module 91 doesthis by identifying the positions of all of the “1s” within the resourceallocation bit pattern 51 to determine the total number of chunksallocated in other groups. For the allocation shown in FIG. 5B, thedecoder module will identify that the group corresponding to resource ID“0” has 6 chunks; that the group corresponding to resource ID “1” has 3chunks and that the remaining 3 groups corresponding to resource IDs“2”, “3” and “4” each have 1 chunk. From this information, the decodermodule 91 determines that the chunks associated with resource ID “0”will be spaced apart by 2 chunks.

In this mode, the distributed chunk allocation scheme is arranged sothat the first chunk within the sub-band is always allocated to thefirst chunk allocated to resource ID “0”. Therefore, for the aboveexample, the allocated chunks for resource ID “0” will be chunks 0, 2,4, 6, 8, and 10. The decoder module 91 then considers the allocatedchunks for resource “1”. As discussed above, the chunk spacing forresource ID “1” is 4. The decoder module 91 then assigns the first chunkfor resource ID “1” as being the first available chunk after the chunksfor resource ID “0” have been allocated. In this example, the firstunallocated chunk is chunk 1 and therefore, the chunks allocated toresource ID “1” will be chunks 1, 5 and 9. In a similar manner, thefirst chunk that is available for allocation for resource ID “2” ischunk 3 etc.

As those skilled in the art will appreciate, as the groups of chunkshave been ordered so that the largest groups have the lowest resourceIDs 53 than its own, in this mode, the mobile telephone 3 only needs toconsider the chunk allocations for the groups with a lower resource ID53, when determining the position of its first allocated chunk in thesub-band.

If at step s31, the decoder module 91 determines that the two bitallocation type pattern does not corresponded to a distributed chunkallocation, then the decoder module 91 determines that the allocationcorresponds to a distributed sub-carrier allocation as illustrated inFIG. 5C. In this case the processing proceeds to step s35, where thedecoder module 91 determines the number of sub-carriers assigned to themobile telephone 3 by multiplying the number of chunks in the assignedgroup by the number of sub-carriers in each chunk (i.e. by twenty five).The decoder module 91 also calculates the spacing between thesub-carriers by dividing the total number of chunks in the sub-band bythe number of chunks in the allocated group. The position of the firstsub-carrier is then determined to be the first sub-carrier availableafter the sub-carriers have been assigned for groups associated withresource IDs having lower values, in a similar way to the way in whichthe starting chunk was determined in the distributed chunk allocationprocessing described above.

After the decoder module 91 has determined its sub-carrier allocation(either in step s29, step s33 or step s35), the decoder module 91 sendsappropriate control signals to the transceiver circuit 71 to control thereception of data using the identified sub-carriers. The processing thenends.

Second Encoding Technique

A second encoding technique that the encoder module 35 within the basestation 5 can use to encode the above described resource allocationinformation will now be described with reference to FIGS. 4, 9 and 10.As illustrated in FIG. 4, the 20 MHz operating bandwidth of the basestation 5 can be divided into sub-bands of different sizes, with thesmallest sub-band corresponding to a bandwidth of 1.25 MHz. The numberof chunks available for each sub-band is given in the table below:

Sub-Band Bandwidth (MHz) 1.25 2.5 5 10 15 20 Number Of 3 6 12 24 36 48Chunks

In this second encoding technique, a triangular code tree is used withthe number of chunks available for a particular bandwidth equal to thenumber of leaf nodes at the base of the code tree. For the example of a2.5 MHz sub-band shown in FIG. 9, which has 6 chunks, the correspondingcode tree is illustrated in FIG. 10. As shown, the code tree 91 isformed from a tree of nodes having a depth of N nodes corresponding tothe number of chunks within the sub-band and having N leaf nodes in thebottom row of the code tree 91. In this example, there are six chunksand therefore, the tree has a depth of 6. The total number of nodeswithin the tree equals N(N+1)/2. A node number from this tree cantherefore be signalled using ceil (log.sub.2(N*(N+)/2)) number of bits.The exact number of bits required for each bandwidth is shown in thetable below:

MHz 1.25 2.5 5 10 15 20 N 3 6 12 24 36 48 Number Of Bits 3 5 7 9 10 11

In this mode, the node numbering is designed to optimise the number ofsignalling bits required to signal a particular resource allocation. Inthe example illustrated in the FIGS. 9 and 10, for a 2.5 MHz bandwidth,a five bit number is signalled to uniquely determine the starting chunkand the number of consecutive chunks allocated (which identifies the endchunk). In the general case where there are N chunks within thesub-band, the starting chunk (O) and the number of consecutive chunks(P) that are allocated can be signalled as an unsigned integer x asfollows:

${{if}\mspace{14mu}\left( {P - 1} \right)} \leq \left\lceil \frac{N}{2} \right\rceil$  x = N(P − 1) + O else   x = N(N − (P − 1)) + (N − 1 − O)where ┌r┐ is the ceiling function, i.e., the smallest integer not lessthan r.At the receiver, the values of P and O can be then be extracted asfollows:

$a = {\left\lfloor \frac{x}{N} \right\rfloor + 1}$ b = x mod Nif (a + b > N)   P = N + 2 − a   O = N − 1 − b else   P = a   O = bwhere └r┘ is the floor function, ie the largest integer not greater thanr.

One advantage with this encoding technique is that no look up table (orcode tree structure) is required to carry out the encoding or decoding.Further, the division by N performed by the receiver can also beimplemented by a simple multiplication and shift operation.

For localised chunk allocation, each mobile telephone 3 will besignalled a node number, which maps to a set of leaf chunks. As anexample, if one mobile telephone 3 is allocated chunks 0 and 1, anothermobile telephone is allocated chunks 2, 3 and 4 and a third mobiletelephone 3 is allocated chunk 5 from the 2.5 MHz bandwidth illustratedin FIG. 9, then the first mobile telephone 3 will be signalled the value6, the second mobile telephone 3 will be signalled the value 14, and thethird mobile telephone 3 will be signalled the value 5. These values arepreferably determined using the first equation given above.Alternatively, these node numbers can be determined from the treestructure 91 by identifying the root node that is common to theallocated chunks. For example, for the first mobile telephone 3, wherethe allocated chunks correspond to chunks 0 and 1, the root node that iscommon to these nodes is the node numbered 6. Similarly, for the secondmobile telephone 3, which has been allocated chunks 2, 3 and 4, the nodewhich is the common root for the starting chunk 2 and the end chunk 4 isthe node numbered 14. Finally, for the third mobile telephone that hasbeen allocated chunk 5, since there is only 1 chunk, there is no commonnode and therefore the node number that is signalled corresponds to theallocated chunk number (i.e. 5).

In the case of a distributed chunk allocation for the same bandwidth,the same equations can be used to signal the chunks that have beenallocated. For example, if a mobile telephone 3 is allocated chunks 1and 5, then the number 16 is signalled together with a distributed chunkallocation indicator. At the mobile telephone, the P and O values aredecoded in the same manner as discussed above, however, theirinterpretation is different. In particular, with distributed chunkallocation, the value of P denotes the chunk spacing and the value of Odenotes the first chunk in the distributed allocation.

Multiplexing of distributed chunk allocation and localised chunkallocation at the same time point is also easily supported using thisencoding method. For example, one mobile telephone 3 may allocated alocalised allocation and signalled the value 14, which maps to chunks 2,3, and 4 whilst another mobile telephone is allocated a distributedchunk allocation and signalled the value 16, which maps to chunks 1 and5.

Distributed sub-carrier allocation with different spacing for differentmobile telephones can also be supported using the above encoding scheme.In this case, the values of O and P are also interpreted in a differentway. In this case, as distributed sub-carrier allocation has beenselected, the value of O will identify the allocated sub-carrier offsetand the value of P will define the spacing between the sub-carriers. Forexample, if a mobile telephone 3 is signalled the value 16 and anindication that distributed sub-carrier allocation has been made, thenthe sub-carrier offset will be 1 and the sub-carrier spacing will be 5.Similarly, a mobile telephone 3 signalled the value 14 and a distributedsub-carrier indicator will assume a sub-carrier offset of 2 and asub-carrier spacing of 3. As those skilled in the art will appreciatemultiplexing of localised chunk and distributed sub-carrier is notpossible with this encoding technique.

Although the above examples illustrate the situation for a 2.5 MHzsub-band, this is for ease of illustration only. Resource allocationwithin the base station's total bandwidth can be accomplished in unitsof the downlink reception capability of the different mobile telephones3. For example, if all mobile telephones 3 can receive at least 5 MHz,then the resource allocation at the base station 5 can be done in unitsof 5 MHz. Larger bandwidth mobile telephones 3 can then combine controlchannels over multiple 5 MHz bands to decide their resource allocation.

MODIFICATIONS AND ALTERNATIVES

A number of detailed modes have been described above. As those skilledin the art will appreciate, a number of modifications and alternativescan be made to the above modes whilst still benefiting from theinventions embodied therein. By way of illustration only a number ofthese alternatives and modifications will now be described.

In the above modes, a mobile telephone based telecommunication systemwas described in which the above described signalling techniques wereemployed. As those skilled in the art will appreciate, the signalling ofsuch resource allocation data can be employed in any communicationsystem that uses a plurality of sub-carriers. In particular, thesignalling techniques described above can be used in wire or wirelessbased communications either using electromagnetic signals or acousticsignals to carry the data. In the general case, the base station wouldbe replaced by a communication node which communicates with a number ofdifferent user devices. User devices may include, for example, personaldigital assistants, laptop computers, web browsers, etc.

In the above modes, the base station was assumed to have an operatingbandwidth of 20 MHz (which was divided into a number of sub-bands) andthe chunks of carrier frequencies were defined to comprise 25sub-carriers each. As those skilled in the art will appreciate, theinvention is not limited to this particular size of bandwidth or chunksize or to the size of the sub-bands described.

In the first encoding technique described above, the base stationpartitioned the chunks within the sub-band into a number of groups. Thebeginning and end of these groups were then identified by bits within aresource allocation bit pattern. In the example, a “1” within this bitpattern represented the beginning of a new group. As those skilled inthe art will appreciate, other encoding schemes could be used. Forexample, a “0” could be used to define the start of each group.Alternatively, a change in bit value may be used to define the start ofeach group.

In the first encoding technique described above, the resource IDallocated for each sub-band was transmitted to each mobile telephoneover a dedicated signalling channel. As those skilled in the art willappreciate, this resource ID information may instead be signalled withinthe common signalling channel. In this case, the user devices IDcorresponding to each resource ID will be signalled within the commonsignalling channel, so that each user device can identify the resourceID allocated to it.

In the first encoding technique described above, the base station andmobile telephone implicitly numbered the groups and the chunks from leftto right within the sub-band. As those skilled in the art willappreciate, this is not essential. The numbering of the groups andchunks may be performed in other ways such as from right to left.Provided both the base station 5 and the mobile telephones 3 know thenumbering scheme in advance, the above encoding can be carried out.

In the above encoding schemes, the base station 5 was able to allocatesub-carriers using a number of different allocation techniques. As thoseskilled in the art will appreciate, one or more of these allocationtechniques may be dispensed with. Further, if only one allocationtechnique is used, then there is no need to signal a separate allocationtype bit pattern.

In the second encoding technique described above, a mapping was definedbetween the chunks and a unique number which represented the combinationof a start chunk and an end chunk within a sequence of chunks allocatedto the user. As those skilled in the art will appreciate, this mappingmay be defined in any appropriate way, such as using an equation orusing a lookup table. The use of an equation is preferred as it removesthe need to store a lookup table both in the base station 5 and in eachof the mobile telephones 3.

In the above modes, a number of software modules were described. Asthose skilled will appreciate, the software modules may be provided incompiled or un-compiled form and may be supplied to the base station orto the mobile telephone as a signal over a computer network, or on arecording medium. Further, the functionality performed by part or all ofthis software may be performed using one or more dedicated hardwarecircuits. However, the use of software modules is preferred as itfacilitates the updating of base station 5 and the mobile telephones 3in order to update their functionalities.

It should be noted that other objects, features and aspects of thepresent invention will become apparent in the entire disclosure and thatmodifications may be done without departing the gist and scope of thepresent invention as disclosed herein and claimed as appended herewith.

Also it should be noted that any combination of the disclosed and/orclaimed elements, matters and/or items may fall under the modificationsaforementioned.

What is claimed is:
 1. A communications node which communicates with acommunications device, the communications node comprising: a memorystoring instructions; one or more processors configured to execute theinstructions to: transmit control information which comprises a resourceindication value, wherein the resource indication value is defined by atleast one of expressions:N(P−1)+OandN(N−(P−1))+(N−1−O) where N is the number of resource blocks in abandwidth, O is a starting resource block number and P is the length interms of number of consecutive resource blocks; and transmit downlinkdata using a downlink channel corresponding to the control information.2. A communications node according to the claim 1, wherein the controlinformation further comprises a first bit pattern which indicates a typeof resource allocation that identifies an allocation of at least oneresource block.
 3. A communications node according to the claim 1,wherein each resource block in the bandwidth comprises subcarriers in asub-frame.
 4. A communications device which communicates with acommunications node, the communications device comprising: a memorystoring instructions; one or more processors configured to execute theinstructions to: receive, from the communications node, controlinformation which comprises a resource indication value, wherein theresource indication value is defined by at least one of expressions:N(P−1)+OandN(N−(P−1))+(N−1−O) where N is the number of resource blocks in abandwidth, O is a starting resource block number and P is the length interms of number of consecutive resource blocks; interpret resourceallocation based on the control information; and decode a downlinkchannel corresponding to the control information.
 5. A communicationsdevice which communicates with a communications node, the communicationsdevice comprising: a memory storing instructions; one or more processorsconfigured to execute the instructions to: receive, from thecommunications node, control information which comprises a resourceindication value, wherein the resource indication value is defined by atleast one of expressions:N(P−1)+OandN(N−(P−1))+(N−1−O) where N is the number of resource blocks in abandwidth, O is a starting resource block number and P is the length interms of number of consecutive resource blocks; interpret resourceallocation based on the control information; and transmit uplink datausing an uplink channel corresponding to the control information.
 6. Acommunications device according to the claim 5, wherein the controlinformation further comprises a first bit pattern which indicates a typeof resource allocation that identifies an allocation of at least oneresource block.
 7. A communications device according to the claim 5,wherein each resource block in the bandwidth comprises subcarriers in asub-frame.
 8. A communications method in a communications node whichcommunicates with a communications device, the communications methodcomprising: transmitting control information which comprises a resourceindication value, wherein the resource indication value is defined by atleast one of expressions:N(P−1)+OandN(N−(P−1))+(N−1−O) where N is the number of resource blocks in abandwidth, O is a starting resource block number and P is the length interms of number of consecutive resource blocks; and transmittingdownlink data using a downlink channel corresponding to the controlinformation.
 9. A communications method in a communications device whichcommunicates with a communications node, the communications methodcomprising: receiving, from the communications node, control informationwhich comprises a resource indication value, wherein the resourceindication value is defined by at least one of expressions:N(P−1)+OandN(N−(P−1))+(N−1−O) where N is the number of resource blocks in abandwidth, O is a starting resource block number and P is the length interms of number of consecutive resource blocks; interpreting resourceallocation based on the control information; and decoding a downlinkchannel corresponding to the control information.
 10. A communicationsmethod in a communications device which communicates with acommunications node, the communications method comprising: receiving,from the communications node, control information which comprises aresource indication value, wherein the resource indication value isdefined by at least one of expressions:N(P−1)+OandN(N−(P−1))+(N−1−O) where N is the number of resource blocks in abandwidth, O is a starting resource block number and P is the length interms of number of consecutive resource blocks; interpreting resourceallocation based on the control information; and transmitting uplinkdata using an uplink data channel corresponding to the controlinformation.